N-Ary Tree Preorder Traversal Problem
Description
LeetCode Problem 589.
Given the root of an n-ary tree, return the preorder traversal of its nodes’ values.
Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)
Example 1:
1
2
Input: root = [1,null,3,2,4,null,5,6]
Output: [1,3,5,6,2,4]
Example 2:
1
2
Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [1,2,3,6,7,11,14,4,8,12,5,9,13,10]
Constraints:
- The number of nodes in the tree is in the range [0, 10^4].
- 0 <= Node.val <= 10^4
- The height of the n-ary tree is less than or equal to 1000.
Sample C++ Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
class Solution {
private:
void travel(Node* root, vector<int>& result) {
if (root == nullptr) {
return;
}
result.push_back(root -> val);
for (Node* child : root -> children) {
travel(child, result);
}
}
public:
vector<int> preorder(Node* root) {
vector<int> result;
travel(root, result);
return result;
}
};